On World AIDS Day, December 1, 2011, the NYC Department of Health and Mental Hygiene (NYCDOHMH) announced a new policy that all HIV seropositives should be offered antiretroviral treatment (ART) regardless of CD4 cell count. The new policy was based primarily on treatment as prevention as a method for not only improving the health of people living with HIV who initiate ART early, but also as a means of reducing transmission of the virus. The NYCDOHMH set an ambitious goal for this new policy: by one year post HIV diagnosis, 80% of new HIV diagnoses will have reached viral suppression. There are over 3,400 new HIV infections occurring annually in NYC; recent data indicate 38% reached durable viral suppression in 2006-07 (i.e., all viral loads 400 copies/mL). The policy goal is ambitious, but if it were to be achieved, it would almost certainly lead to an AIDS-free generation - the central theme of the 2012 International AIDS Conference - in the city with the largest local HIV epidemic in the US. There are serious difficulties in achieving this policy goal, notably the persistent racial/ethnic disparities in HIV infection in the city, especially among African-Americans, and drug-related sexual transmission. The overarching purpose of this research is to provide multisystem data to evaluate the implementation of the policy and help determine the most efficient use of available resources for achieving the policy goal. The design and methods are informed by the ecological systems model, while the RE-AIM model guides the overall assessment of the implementation of the new policy. The study aims are: 1) to assess durable viral suppression (i.e., two consecutive viral load tests 400 HIV-1 RNA copies per mL of plasma) within 12 months of diagnosis among a) STD clinic cohort (N = 300) with problem substance use, and b) all new HIV diagnoses in NYC occurring during the project funding period (N=approximately 3,400/year); 2) to assess key indicators along the HIV treatment cascade among the STD clinic cohort as the percentage who (a) link to HIV care; (b) receive a recommendation to initiate ART; (c) initiate ART treatment; and (d) adhere to ART treatment; 3) to assess multisystem predictors of durable viral load suppression and other HIV treatment cascade indicators among the STD clinic cohort and cohort of all new HIV diagnoses in NYC, to include individual (e.g., race/ethnicity, substance use) and geospatial factors (e.g., socioeconomic conditions, social disorder, social cohesion, and spatial access to HIV-related healthcare); 4) to describe and contextualize quantitative outcomes in Aims 1-3 using STD cohort qualitative data; and 5) to describe the adoption, implementation, and maintenance of HIV treatment policies among HIV primary care providers. The endpoint of durable viral suppression increases